Interlocked.CompareExchange Generic Method (T, T, T)

Note: This method is new in the .NET Framework version 2.0.

Compares two instances of the specified reference type T for equality and, if they are equal, replaces one of them.

Namespace: System.Threading
Assembly: mscorlib (in mscorlib.dll)

public static T CompareExchange<T> (
	ref T location1,
	T value,
	T comparand
J# supports the use of generic types and methods, but not the declaration of new ones.
JScript does not support generic types and methods.

Type Parameters


The type to be used for location1, value, and comparand. This type must be a reference type.



The destination, whose value is compared with comparand and possibly replaced. This is a reference parameter (ref in C#, ByRef in Visual Basic).


The value that replaces the destination value if the comparison results in equality.


The value that is compared to the value at location1.

Return Value

The original value in location1.

Exception typeCondition


The address of location1 is a null pointer.

If comparand and the value in location1 are equal, then value is stored in location1. Otherwise, no operation is performed. The comparison and the exchange are performed as an atomic operation. The return value of this method is the original value in location1, whether or not the exchange takes place.

This method only supports reference types. There are overloads of the CompareExchange method for the value types Int32, Int64, IntPtr, Single, and Double, but there is no support for other value types.


This method overload is preferable to the CompareExchange(Object,Object,Object) method overload, because the latter requires the destination object to be accessed late-bound.

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

.NET Compact Framework

Supported in: 2.0

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